/*
 * Copyright 2008 Georgi Staykov
 * 
 * This file is part of pscoder.
 *
 * pscoder is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * pscoder is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with pscoder.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.gstaykov.pscoder.editor.syntax;

import java.util.HashSet;

import org.eclipse.jface.text.rules.ICharacterScanner;
import org.eclipse.jface.text.rules.IRule;
import org.eclipse.jface.text.rules.IToken;
import org.eclipse.jface.text.rules.Token;

/**
 * @author gstaykov
 *
 */
public class PowershellVariableDetector implements IRule {
	
	IToken scope = Token.UNDEFINED;
	IToken variable = Token.UNDEFINED;
	HashSet<String> predefined = new HashSet<String>();
	StringBuffer buffer = new StringBuffer();
	
	public PowershellVariableDetector(IToken scope, IToken variable) {
		this.scope = scope;
		this.variable = variable;
	}
	
	public void addScope(String scope) {
		predefined.add(scope.toLowerCase());
	}
	
	/** 
	 * @see org.eclipse.jface.text.rules.IRule#evaluate(org.eclipse.jface.text.rules.ICharacterScanner)
	 */
	public IToken evaluate(ICharacterScanner scanner) {
		boolean wasMatchEmpty = (buffer.length() == 0)? true : false;
		int ch = scanner.read();
		if (ch != ICharacterScanner.EOF && ((char) ch == '$' || !wasMatchEmpty)) {
			buffer.setLength(0);
			
			do {
				buffer.append((char) ch);
				ch = scanner.read();
			} while (Character.isJavaIdentifierPart((char) ch));
			
			if ((char) ch == ':') {
				String match = (buffer.toString()).toLowerCase();
				return (predefined.contains(match))? scope : variable;
			} else {
				buffer.setLength(0);
				scanner.unread();
				return variable;
			}
		}
		
		scanner.unread();
		return Token.UNDEFINED;
	}
}